The present invention relates to non-woven fabrics, and more especially to multiple-layered non-woven fabrics which are bonded with synthetic binder filaments and which are useful as backing material for tufted carpets.
It is known to use non-woven fleeces or webs as tuft backing for carpets. For example, in German Auslegeschrift No. 1,635,583 there is described a non-woven fleece as such a tuft backing. A backing material for tufted carpet is built up from a non-woven fleece, the fibers of which are bound with a spectrum of adhesive strengths, whereby however, this spectrum of adhesive strengths is throughout the thickness of the material. The spectrum of the different adhesive strengths is supposed to give rise to the result that the fiber bonds having the lowest adhesive strength loosen themselves during tufting and surround the pile yarn, and the fiber bonds of higher strength produce the mechanical cohesion. However, as a result of the fact that this spectrum of adhesive strengths is symmetrically present throughout the thickness of the material on both sides of the carpet, there arises the disadvantage that the upper side of the backing material facing the pile layer contains a high percentage of fibers of lower fusion, so that when the carpet is later used, these fibers are eliminated from the binding and end up on the visible side of the carpet.
Also, from German Offenlegungsschrift No. 1,760,811 there is known a tuft backing which is formed from a plurality of layers, whereby an anisotropic fiber disposition of the layers in the entire binding of the fleece is chosen, in order to satisfy the different strength requirements during the tufting procedure. It has been shown, however, that this stratified anisotropic construction is detrimental in that the part of the fleece facing the side to be coated is penetrated by the coating material during the anchoring of the tuft-pile yarn, so that the different layers of aniostropically supported fibers are enveloped non-uniformly by binder. This leads to the result that the laying behavior of such carpets is impaired by the strongly defined anisotropy of the carpet.